1. Field of the Invention
This invention generally relates to an image forming apparatus such as a copying machine or the like and, more particularly to a controlling technique of the transfer timing of a batch of documents bound in the style of a book.
2. Description of Related Art
Various kinds of copying modes are made possible in recent copying machines, for example, a one-face copy, a double-face copy, a synthesizing copy, a dividing copy and the like modes. The dividing copy mode referred to above is to copy the spread space of a book stretching from one page over a next page, that is, supposing that the book consists of eight pages, the spread space means the fourth and fifth pages, to one or both surfaces of a copying paper after dividing the spread space in half. The dividing copy mode has been carried out in a conventional copying machine by scanning two times. In other words, every time each half of the spread space is scanned, the image is transferred to the copying paper, thereby obtaining a divided image for every half page.
Meanwhile, for copying a book-type document, the document should be pressed onto a document glass during scanning so as to prevent distortion of the image in the periphery of the binding margin. Therefore, in the case of the above-described dividing copy mode requiring two-times scanning, since the scanning time is approximately two times as long as the general case, the pressing time is correspondingly increased, giving a great deal of burden to an operator.
Particularly, when a man of short stature tries the dividing copy mode, to continue pressing the book-type document cannot be realized without an effort, otherwise the book-type document would be shifted, resulting in a loss or breakage of the image. In such case, copying should be repeated again, thereby wasting a lot of time and copying papers.